Seeking a renewable substitute for petroleum-based energy fuels, much effort has been invested in the production of ethanol from biological sources such as dry grind ethanol processes. Recently a number of attempts have been made to extract oil from the stillage process streams due to its high value as a human consumable product. Surfactants have been utilized in oil separation processes to increase the amount of oil extracted from stillage. Such processes generally involve the use of a surfactant at the water-oil interface of oil droplets to extract the oil droplets from the aqueous phase, followed by separation of the oil by centrifuge.
Grain stillage often comprises entrapped oil, i.e., oil located within or adhered to the surface or other regions of aggregates of solids materials. Entrapped oil is difficult to separate from stillage because solid aggregates can block a surfactant's access to the oil. Grain stillage often has a high solid content, and thus has a large amount of oil trapped within solid aggregates. Extraction of oil trapped in solid aggregates can greatly increase the total amount of oil captured from a stillage process.
There is a need for more efficient and productive methods and compositions for grain to ethanol processes.